In anticipation of the international GEOTRACES program, which will study the global marine biogeochemistry of trace elements and isotopes, we conducted a multi-lab intercomparison for radium isotopes. The intercomparison was in two parts involving the distribution of: (1) samples collected from four marine environments (open ocean, continental slope, shelf, and estuary) and (2) a suite of four reference materials prepared with isotopic standards (circulated to participants as 'unknowns'). Most labs performed well with 228Ra and 224Ra determination, however, there were a number of participants that reported 226Ra, 223Ra, and 228Th (supported 224Ra) well outside the 95% confidence interval. Many outliers were suspected to be a result of poorly calibrated detectors, though other method specific factors likely played a role (e.g., detector leakage, insufficient equilibration). Most methods for radium analysis in seawater involve a MnO2 fiber column preconcentration step; as such, we evaluated the extraction efficiency of this procedure and found that it ranged from an average of 87% to 94% for the four stations. Hence, nonquantitative radium recovery from seawater samples may also have played a role in lab-to-lab variability. © 2012, by the American Society of Limnology and Oceanography, Inc.
CITATION STYLE
Charette, M. A., Dulaiova, H., Gonneea, M. E., Henderson, P. B., Moore, W. S., Scholten, J. C., & Pham, M. K. (2012). GEOTRACES radium isotopes interlaboratory comparison experiment. Limnology and Oceanography: Methods, 10(JUNE), 451–463. https://doi.org/10.4319/lom.2012.10.451
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